A conventional microwave processing device of this kind is provided with a coaxial cable and a periodic structure body. The coaxial cable supplies microwave energy therethrough, and the periodic structure body is supplied with the microwave energy from the coaxial cable and has an interdigital tape line formed therein (see, for example, Patent Document 1). The microwave processing device of Patent Document 1 has a resonant hole defined in an end of the interdigital tape line. In this configuration, an object to be heated is uniformly heated by microwave heating from the resonant hole, while browning the object using microwaves produced in the interdigital tape line.
In another microwave processing device, microwaves are emitted and transmitted through an interdigital tape line formed by a periodic structure body (see, for example, Patent Document 2). Even a thick object to be heated is efficiently microwave-heated by emitting and transmitting the microwaves through the interdigital tape line.